共查询到20条相似文献,搜索用时 15 毫秒
1.
《Catalysis communications》2007,8(5):800-806
Benzylation of phenol with benzylalcohol was carried out in liquid phase over tungstophosphoric acid (TPA) supported on titania. The catalysts were prepared with different TPA (10–25%) loading by wet impregnation method, were calcined at 700 °C and characterized by XRD, surface area, FTIR and acidity of the catalysts was measured by temperature programmed desorption of NH3–TPD, FTIR pyridine adsorption. The catalysts have been represented by a general formula as xPTiO2−y (where x = wt%, P = TPA, and y = calcination temperature in °C). The 20PTiO2 catalyst calcined at various temperatures to know the effect of calcination temperature on activity of the catalyst and the 20PTiO2-700 showed highest activity in benzylation of phenol with benzylalcohol because it had highest acidity. The effects of temperature, catalyst weight, mole ratio of the reactants on conversion of phenol and product selectivities have been optimized. 20PTiO2-700 catalyst gave conversion of benzylalcohol (BA) 98% and the selectivity to benzyl phenol (BP) 83.6%, phenyl benzyl ether (PBE) 9.4%, benzylether (BE) 7% at 130 °C, phenol to benzylalcohol molar ratio 2 and in 1 h. 相似文献
2.
A. de Angelis C. Flego P. Ingallina L. Montanari M. G. Clerici C. Carati C. Perego 《Catalysis Today》2001,65(2-4):363-371
A thermally stable solid acid catalyst has been prepared by treating amorphous silica gel with trifluoromethanesulphonic (triflic) acid (TFA) at 150°C in a closed glass vessel. A solvent such as 1,1,2-trichloro-2,2,1-trifluoro-ethane (Freon 113) can be conveniently used to dissolve TFA. The obtained material is an active catalyst in the alkylation of isobutane with n-butenes to yield high-octane gasoline components. In the reaction it behaves like a truly solid catalyst not leaching TFA in the solution for about 24 h. The catalyst characterisation has been performed by 1H- and 19F-NMR and IR spectroscopy. 相似文献
3.
开发新负载型碳三馏分选择加氢催化剂,针对液相加氢工艺特点,在侧线装置上摸索和测试各种操控及运行参数,指导并首次成功应用于770kt/a乙烯装置。通过对催化剂的机械强度、催化性能以及操作窗口考察和研究,发现新型BC-L-83G催化剂的耐磨损、抗破碎以及长周期运行能力都大大优于上一代BC-L-83催化剂,并具有良好的温度适应性和氢炔比敏感度。工业应用的12个月试验结果表明,BC-L-83G具有催化活性高、选择性好、抗波动能力强、再生周期长等优势,非常适合进一步推广使用。 相似文献
4.
5.
6.
7.
8.
9.
阐述了固体酸烷基化催化剂在异丁烷/丁烯烷基化中的再生方法研究进展,包括金属临氢再生、氧化煅烧再生、超临界流体再生、洗涤再生,同时对固体酸烷基化催化剂的失活原因和失活形式进行了分析评述。这些方法在一定条件下可以实现催化剂不同程度的再生,但由于操作以及成本等原因都停留在实验室阶段,本文综合比较了各种再生方法的再生工艺过程以及再生效果,分析各种再生方法的优劣。固体酸烷基化催化剂失活较快是阻碍异丁烷/丁烯固体酸烷基化工艺工业化的关键因素,研究探索操作简单、成本低、有效的固体酸烷基化催化剂再生方法仍将是今后该领域的研究热点。 相似文献
10.
The deactivation of solid acid catalysts in liquid phase alkylation of isobutane with 2-butene was investigated. Since under liquid phase conditions the alkylation reaction is severely diffusion limited, effects of diffusion on the rate of reaction and deactivation pathways were considered. In the present work, an attempt has been made to implement more appropriate assumptions in order to properly model catalyst deactivation in a mixed reactor. Accordingly, spatial variation of diffusivity in the pores of the catalyst was considered as a function of time on stream. The effect of the pore mouth plugging was also investigated and it was found that this phenomenon had a pronounced effect on the deactivation behavior of the catalyst. An empirical order of deactivation was determined through a power-law expression for alkylation over a faujasite (FAU) zeolite. 相似文献
11.
Agnès Choplin Silvia Dos Santos Françoise Quignard Silvana Sigismondi Denis Sinou 《Catalysis Today》1998,42(4):716-478
The reaction of allylic carbonates with various acyclic and cyclic carbonucleophiles is catalyzed by the system Pd(OAc)2 and P(C6H4-m-SO3Na)3 (or tppts) in a two-phase liquid medium H2O-nitrile, the activity of the catalyst depending mainly on the nature of the nitrile, the temperature of the reaction and the ratio palladium/tppts. The same system Pd(OAc)2 and P(C6H4-m-SO3Na)3 supported on silica catalyzes also this reaction. The formation of the active palladium species in the two cases is followed by NMR spectroscopy and discussed. 相似文献
12.
采用浸渍法制备TPA/Nb2O5催化剂,用于油酸与甲醇的酯化反应,考察了催化剂焙烧温度、甲醇与油酸物质的量比、反应时间、催化剂用量和TPA负载量等因素对油酸转化率的影响。结果显示,低负载量时(ω=5,10,15),TPA杂多阴离子高度均匀地分散在Nb2O5表面,随着负载量的增加,TPA在Nb2O5表面出现聚结。25-TPA/Nb2O5(300)催化剂在油酸与甲醇的酯化反应中具有良好的催化活性,在n(甲醇)/n(油酸)=12,m(催化剂)/m(油酸)=7%,反应时间在6 h的条件下,油酸的转化率高达92.24%。在303~333 K范围内,油酸的转化率随着温度的升高逐渐增大,油酸与甲醇在TPA/Nb2O5催化剂上的酯化反应符合准二级动力学方程,表观活化能为57.62 kJ/mol,指前因子为1.096×109(mol/L)-1.h-1。 相似文献
13.
Polyaniline‐supported acid salts such as polyaniline‐hydrochloride, polyaniline‐sulfate, and polyaniline‐nitrate were prepared by oxidation of aniline using benzoyl peroxide and ammonium persulfate as oxidizing agents. Polyaniline salts were used as catalysts in the esterification of cinnamic acid with alcohols. Polyaniline‐sulfate salt was found to be the best catalyst for the esterification of cinnamic acid. The reusability, handling, and recovery of the catalyst were found to be good. The yield of the ester depended on the type of the polyaniline salt, amount of the catalyst, amount of alcohol, and both the time and the temperature of the reaction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1584–1590, 2005 相似文献
14.
15.
综述了近十年来液体酸耦合体系催化C4烃烷基化反应的最新进展,包括液体超强酸、有机酸-杂多酸、离子液体-酸耦合体系,对比了不同催化体系催化C4烃烷基化反应过程中的烯烃转化率、三甲基戊烷的选择性和烷基化汽油的研究法辛烷值,总结了不同催化体系的优缺点。重点论述了离子液体-酸耦合体系催化剂中组成离子液体的阴阳离子以及耦合酸类型对C4烃烷基化反应的影响:有机胺类离子液体较咪唑类有着更为优异的烷基化效果,阴离子和改性离子液体通过形成特定的结构来维持反应体系的酸强度、减少副反应,从而延长催化剂的使用寿命,耦合酸为反应提供酸性位点并与离子液体协同催化。离子液体-酸耦合催化体系具有酸耗低、稳定性好、不易失活且可循环使用等优点,是C4烷基化催化剂未来的发展方向之一。 相似文献
16.
17.
Mesocellular silicon foam supported poly(chloromethylstyrene-co-divinylbenzene) (MCF–copolymer) was synthesized. It has a pore size of 24.2 nm. The pore volume and the surface area were 0.84 cm3/g and 246.9 m2/g, respectively. MCF–copolymer supported sulfonic acid was accomplished via sulfonation with concentrated sulfuric acid. The acid amount on the MCF–copolymer was 2.03 mmol/g. Hydrolysis of banana pseudo-stem fibers and microcrystalline cellulose was carried out over the catalyst. The large pore size favors the diffusion of molecules in catalyzing bulky molecules. The corresponding catalytic turnover frequencies (TOF) were 5.57 h− 1 and 8.066 h− 1. 相似文献
18.
对C3馏份选择加氢催化剂及工艺条件进行了研究,试验结果表明,含有3.17%(物质的量的含量)丙炔和丙二烯的C3馏份经催化精馏加氢,塔顶C3馏份中的炔烃、二烯烃可脱至≤10μg/g,丙烯收率≥102%。经262h考核,催化剂仍保持良好的活性和选择性。 相似文献
19.
POSS supported prolinamide-type catalysts were synthesized and used to catalyze asymmetric Aldol reactions between unmodified ketones and aldehydes. Immobilization of the prolinamide-type catalysts onto POSS resulted in good yields and improved diastereoselectivity as well as enantioselectivity. The POSS-supported catalysts were recycled simply by precipitation and filtration, and could be reused in five consecutive cycles without losing its effectiveness. 相似文献